THEORY OF EVOLUTION Chapter 15. Evolution Development of new organisms from pre-existing ones...
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Transcript of THEORY OF EVOLUTION Chapter 15. Evolution Development of new organisms from pre-existing ones...
THEORY OF EVOLUTIONChapter 15
Evolution • Development of new organisms from pre-existing ones• Heritable change in the characteristics within a
population from one generation to the next• Charles Darwin published “On the Origin of the Species”
in 1859• descent with modification (DwM)
Descent with modification (DwM)• Every species must have
descended by reproduction from preexisting species
• Species must be able to change over time
Natural selection• Mechanism for DwM• Four main parts of Darwin’s reasoning
1. Overproduction: more offspring produced than can survive
2. Genetic variation: individual within a population have different traits
3. Struggle to survive: individuals compete• Some variations improve chance for survival and reproduction• Adaptation: trait that makes an individual successful in its
environment
Natural selection
4. Differential reproduction: organisms with best adaptations are most likely to survive and reproduce• Through inheritance, adaptations become more frequent
in a population• This leads to change in a population• Fitness: measure of an individual’s heredity contribution
to the next generation• More than survival• Must reproduce offspring that will reproduce in turn
Notebook assignment: See page 300
Contributors to Darwin• Before Darwin’s time, most
scientist thought the earth and it’s organisms were permanent and unchanging
• Earth was thought to only be thousands of years old• How old is it actually?• About 4.5 Billion years old
• Geologists started to identify the actual age of the earth by looking at the rock strata: rock layers
• Oldest layers on bottom
Contributors • French anatomist Georges Cuvier
• Reconstructed fossils• Some organisms in the past differed greatly form any living
species• “sudden changes” result of CATASTROPHISM >> caused
extinction
• English geologist Charles Lyell• UNIFORMITARIANISM
• the theory that changes in the earth's crust during geological history have resulted from the action of continuous and uniform processes
• French biologist Jean Baptiste Lamarck• INHERITANCE OF ACQUIRED CHARACTERISTICS
• is the idea that an organism can pass on characteristics that it acquired during its lifetime to its offspring
Inheritance of Acquired Characteristics
Fossil record• Fossil: remains or
traces of past life• Fossils show that
different organisms have appeared at different times and places on Earth
• Superposition: oldest rocks on the bottom
How old is it?• Relative vs absolute age• Which is older: A fossil at A or F?• If a radioactive isotope has a half-life
of 50 years, how much is left after 250 years if the original amount was 5,000 mg? Half-lifes Mass
remaining
0 5000 mg
1 (50 years) 2500 mg
2 (100 years
1250 mg
3 (150 years)
625 mg
4 (200 years)
312.5 mg
5 (250 years)
156.25 mg
Transitional species• Intermediate species between ancestral species and later
descendants• Page 304
Biogeography • Studies why living things are found where they are• Unrelated organisms with similar features
Comparative anatomy• Homologous structures: found in related species that
share a common ancestor• May have different functions but similar structure• Analogous structures: related functions, but different
structure
Vestigial structures• Structures with no current function• May have been functional in ancestral species
Evolution in action• Evolution is continuous and
ongoing• Scientists can study
evolutionary patterns today• Case study: anole lizards
• Page 308
Convergent evolution• Process by which different species evolve similar traits
Divergence and radiation• Divergent evolution: process in which descendants of a
single ancestor diversify into species that each fit into different parts of their environment
Adaptive radiation• Many species evolve from a single ancestral species
Artificial selection• Selective breeding of
organisms for specific traits• DONE BY HUMANS!!!• This is in contrast to natural
selection in which the environment places pressure on certain traits
Coevolution
• When two or more species have evolved adaptations to each other’s influence
• Why are flowers different colors?• Why do they have different scents?• Why are flowers shaped differently?• Why do we keep having to develop new antibiotics?• Methicillin Resistant Staphylococcus aureus• MRSA